. . "A kinetic study on the reactions of the OH radical and ozone with acetylacetone (AcAc) has been performed in a 1080 L quartz glass reaction chamber using in situ FTIR spectroscopy analysis. Temperature dependent rate coefficients for the reaction of AcAc with the OH radical were determined over the temperature range 285\u2212310 K using the relative kinetic method. The following Arrhenius expression was derived: k = 3.35 \u00D7 10\u221212 exp((983 \u00B1 130)/T) cm3 molecule\u22121 s\u22121, where the indicated error is the two least-squares deviation. A rate coefficient (in units of cm3 molecule\u22121 s\u22121) of (1.03 \u00B1 0.31) \u00D7 10\u221218 has been obtained at (298 \u00B1 3) K for the reaction of ozone with AcAc. A product investigation on the gas-phase reaction of OH radical with AcAc was conducted in a 405 L borosilicate glass chamber using in situ FTIR spectroscopy to monitor reactants and products. Methylglyoxal, acetic acid, peroxy acetic nitrate (PAN) were positively identified as products with molar yields of (20.8 \u00B1 4.5)%, (16.9 \u00B1 3.4)%, and (2.0 \u00B1 0.5)%, respectively. From the residual infrared spectrum the main products are attributed to 2,3,4-pentantrione (CH3\uE5F8CO\uE5F8CO\uE5F8CO\uE5F8CH3) and its hydrated analogue pentan-2,3-dione-4-diol (CH3\uE5F8CO\uE5F8CO\uE5F8C(OH)2\uE5F8CH3). Based on the observed products, a simplified mechanism for the reaction of the OH radical with AcAc is proposed." . . . . . . "Atmospheric Chemistry of Acetylacetone" . . . . . . . "Kinetic and mechanistic studies of the reactions of OH radicals and ozone with acetylacetone performed in photoreactors at atmospheric pressure and different temperatures are reported." . . . . . . . .